붕소주입탱크(BIT) 제거의 장기 노심 냉각에 미치는 영향에 관한 연구

Abstract

ABSTRACT

A Study on the Influence of Boron Injection Tank Removal on (Post) LOCA Long-term core cooling for Yonggwang NPP #1, 2

By Park, Jeong Jin Adviser : Prof. Song, Jong Sun, Ph. D. Department of Nuclear Engineering, Graduate School of Chosun University

Boron injection tank of Younggwang Units 1/2 contains boric acid solution with a 20,000ppm of boron concentration with 900 gallons of volume. Original design of BIT is to prevent return to power to criticality after a main steam line break event. Because of high boron concentration in BIT system, it is necessary for the design improvement to mitigate burden of maintenance such keeping high temperature with heat tracing to prevent boric acid precipitation for relating systems. Elimination of the BIT would result in a situation in which SI water from the lower boron concentration RWST(2,450ppm) provides the primary means of boration needed to achieve adequate shutdown margin for these rapid cooldown events. Following analyses should be performed to eliminate BIT. And technical bases for design modification will be prepared in this study. ○ Evaluation of Post LOCA Long-term core cooling - Confirmation of core subcriticality - Prevention of boric acid precipitation in core - Confirmation of minimum safety injection flow